A thermoplastic elastomer composition superior in balance between anti-air permeability and flexibility is known, which comprises a specific thermoplastic resin continuous phase and a specific robber elastomer component dispersed therein as a discontinuous phase (Japanese Unexamined Patent Publication. No. 8-259741). In addition, it is known that by having a melt viscosity (ηm) of a thermoplastic resin component and a melt viscosity (ηd) of a rubber elastomer component in the thermoplastic elastomer composition and the difference in solubility parameter (ΔSP) between the elastomer component and the thermoplastic resin component to satisfy a specific relationship, a high elastomer component proportion is achieved, and thereby a thermoplastic elastomer composition having an increased flexibility and excellent anti-gas permeability is obtained, and a pneumatic tire using the same in a gas permeation preventing layer is also known (Japanese Unexamined Patent Publication No. 10-2537.5). Further, there is also known a thermoplastic elastomer composition having an improved anti-gas permeation properties as well as flexibility, oil resistance, cold resistance, and heat resistance by the presence of a barrier resin composition having such a phase structure as the barrier resin composition is dispersed in a flat shape in an elastomer composition comprising a thermoplastic resin as a continuous phase and a rubber composition as a dispersed phase (Japanese Unexamined Patent Publication No. 10-114840). Moreover, there is also known a thermoplastic elastomer composition comprising a polyamide resin modified with a laminar clay mineral and a halogenated isoolefin-paraalkylstyrene copolymer dispersed therein (Japanese Unexamined Patent Publication No. 2000-160024).